Wafer-Level Underfill and Over-Molding
A mold includes a top portion, and an edge ring having a ring-shape. The edge ring is underlying and connected to edges of the top portion. The edge ring includes air vents. The edge ring further encircles the inner space under the top portion of the mold. A plurality of injection ports is connected to the inner space of the mold. The plurality of injection ports is substantially aligned to a straight line crossing a center of the top portion of the mold. The plurality of injection ports has different sizes.
This application is a divisional of U.S. patent application Ser. No. 13/411,293, entitled “Wafer-Level Underfill and Over-Molding,” filed on Mar. 2, 2012, which application is incorporated herein by reference.
BACKGROUNDIn the packaging of integrated circuits, package components, such as device dies and package substrates, are typically stacked through flip chip bonding. To protect the solder regions between the stacked package components, an underfill is disposed between the stacked package components. A molding compound may then be molded on the stacked package components through over-molding.
The conventional molding methods include compression molding and transfer molding. Compression molding may be used for the over-molding. Since the compression molding cannot be used to fill the underfill into the gaps between the stacked dies, the underfill needs to be dispensed in separate steps other than the compression molding. On the other hand, transfer molding may be used to fill a molding underfill into the gap between, and over, the stacked package components. Accordingly, transfer molding may be used to dispense the underfill and the molding compound in the same process step. Transfer molding, however, cannot be used on the packages including round wafers due to non-uniform dispensing of the molding compound.
For a more complete understanding of the embodiments, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The making and using of the embodiments of the disclosure are discussed in detail below. It should be appreciated, however, that the embodiments provide many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are illustrative, and do not limit the scope of the disclosure.
An apparatus for wafer-level molding and the method of performing the wafer-level molding are provided in accordance with various exemplary embodiments. The variations of the embodiments are discussed. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements.
Mold 26 includes top portion (a cover) 26A, which may have a round top-view shape (
As shown in
Edge ring 26B of mold 26 includes a plurality of air vents 32, which are through holes connecting the inner space of mold 26 to the external space. Air vents 32 are used to allow the venting of the air in the inner space of mold 26. Air vents 32 may be distributed throughout edge ring 26B. In some embodiments, air vents 32 are used to vacuum the inner space of mold 26, so that it is easy for molding material 34 to flow from the center of mold 26 to the edge. With the venting/vacuuming through air vents 32, it is less likely to have air bubbles formed in the resulting dispensed molding material 34.
In some embodiments, injection ports 30 are substantially aligned to straight line 31, which crosses center 38 of the top portion 26A of round mold 26. Molding material 34 (
In some exemplary embodiments, molding material 34 may be injected through injection ports 30 simultaneously. In alternative embodiments, molding material 34 is injected from different injection ports 30 at different times. In some exemplary embodiments, center port 30-1 starts injecting molding material 34 first, while other injection ports 30 lag behind in injecting than the respective inner ports. Edge ports 30-n may start injecting at a time after all the inner injection ports 30 have started injecting. In some exemplary embodiments, the staring injection time of edge ports 30-n may lag the starting injection time of center port 30-1 by a time difference greater than about 70 seconds.
In the embodiments, through the adjustment of the sizes of the injection ports, the sizes of the air vents, and/or the starting times of the injection through different injection ports, the molding material may be dispensed at a greater rate to the center of the package than to the edge portions. Accordingly, a more uniform molding may be achieved.
In accordance with embodiments, a mold includes a top portion, and an edge ring having a ring-shape. The edge ring is underlying and connected to edges of the top portion. The edge ring includes air vents. The edge ring further encircles the inner space under the top portion of the mold. A plurality of injection ports is connected to the inner space of the mold. The plurality of injection ports is substantially aligned to a straight line crossing a center of the top portion of the mold. The plurality of injection ports has different sizes.
In accordance with other embodiments, a mold includes a top portion having a round edge, and an edge ring connected to the round edge of the top portion. The top portion and the edge ring of the mold define an inner space therein. A plurality of air vents penetrates through the edge ring of the mold, wherein the plurality of air vents have different sizes. A center injection port penetrates through the top portion of the mold and connected to the inner space of the mold. The center injection port is substantially aligned to the center of the top portion of the mold.
In accordance with yet other embodiments, a method includes providing a mold including a top portion, and an edge ring underlying and connected to the top portion. The edge ring encircles an inner space underlying the top portion. A package structure is placed into the inner space. The package structure includes a wafer, and a plurality of dies bonded to the wafer. At a first time, a molding material starts to be injected into the inner space from a first injection port that penetrates through the top portion of the mold. At a second time later than the first time, the molding material starts to be injected into the inner space from a second injection port that penetrates through the top portion of the mold. The second injection port is farther away from a center of the top portion of the mold than the first injection port.
Although the embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. In addition, each claim constitutes a separate embodiment, and the combination of various claims and embodiments are within the scope of the disclosure.
Claims
1. A method comprising:
- placing a package structure into an inner space of a mold, with the mold comprising a top portion, and an edge ring underlying and connected to the top portion, wherein the edge ring encircles the inner space underlying the top portion; and
- injecting a molding material into the inner space from a first injection port and a second injection port of the mold, with the first injection port and the second injection port having different sizes.
2. The method of claim 1, wherein the first injection port and the second injection port penetrate through the top portion of the mold.
3. The method of claim 1 further comprising evacuating air from the inner space through an air vent on the edge ring.
4. The method of claim 1, wherein the molding material is injected into the inner space from the first injection port earlier than from the second injection port.
5. The method of claim 4, wherein the first injection port is closer to a center of the top portion of the mold than the second injection port.
6. The method of claim 1, wherein the first injection port is closer to a center of the top portion of the mold than the second injection port, and more molding material is injected through the first injection port than through the second injection port.
7. The method of claim 1, wherein during the injecting the molding material, the mold is placed in a vacuumed environment.
8. The method of claim 1, wherein the molding material is injected into the inner space from the first injection port and the second injection port starting at a same time.
9. The method of claim 1 further comprising a plurality of air vents disposed on the edge ring, with the plurality of air vents having different sizes.
10. The method of claim 9, wherein the first injection port and the second injection port are aligned to a straight line, and a first one of the plurality of air vents having a first distance from the straight line has a greater size than a second one of the plurality of air vents having a second distance from the straight line, with the first distance greater than the second distance.
11. A method comprising:
- placing a package structure into an inner space of a mold, with the mold comprising a top portion, and an edge ring underlying and connected to the top portion, wherein the edge ring encircles the inner space underlying the top portion;
- at a first time, start dispensing a molding material into the inner space from a first injection port, wherein the first injection port penetrates through the top portion of the mold; and
- at a second time later than the first time, start dispensing the molding material into the inner space from a second injection port, wherein the second injection port penetrates through the top portion of the mold, and the second injection port is farther away from a center of the top portion of the mold than the first injection port.
12. The method of claim 11, wherein during a period of time between the first time and the second time, the molding material is not dispensed into the space from the second injection port.
13. The method of claim 11 further comprising dispensing the molding material through a plurality of injection ports that are aligned to a straight line, wherein the plurality of injection ports is located between the first and the second injection ports, and wherein the plurality of injection ports starts to inject the molding material at time points later than the first time, and earlier than the second time.
14. The method of claim 11, wherein the first injection port has a size greater than a size of the second injection port.
15. The method of claim 11 further comprising venting from the inner space through a plurality of air vents penetrating through the edge ring of the mold, wherein the plurality of air vents has different sizes.
16. The method of claim 11, wherein the molding material is dispensed into gaps between the plurality of dies.
17. The method of claim 11, wherein the package structure comprises:
- a wafer; and
- a plurality of dies bonded to the wafer, with the molding material dispended in to spaces between the plurality of dies.
18. A method comprising:
- placing a package structure into an inner space of a mold, with the mold comprising a top portion, and an edge ring underlying and connected to the top portion, wherein the edge ring encircles the inner space underlying the top portion; and
- injecting a molding material into the inner space from a first injection port and a second injection port, wherein the first injection port and the second injection port penetrate through the top portion of the mold, and more of the molding material is injected through the first injection port than through the second injection port.
19. The method of claim 18, wherein the first injection port is closer to a center of the top portion of the mold than the second injection port.
20. The method of claim 18, wherein a first starting time the molding material is injected into the inner space from the first injection port is earlier than a second starting time the molding material is injected into the inner space from the second injection port.
Type: Application
Filed: Jan 19, 2015
Publication Date: May 14, 2015
Patent Grant number: 9893044
Inventors: Bor-Ping Jang (Chu-Bei), Chung-Shi Liu (Hsin-Chu), Chien Ling Hwang (Hsin-Chu), Yeong-Jyh Lin (Caotun Township)
Application Number: 14/599,815
International Classification: H01L 25/00 (20060101);